Fabric, especially clothing, can become soiled with a variety of foreign substances ranging from hydrophobic stains (grease, oil) to hydrophilic stains (clay). The level of cleaning which is necessary to remove said foreign substances depends to a large degree upon the amount of stain present and the degree to which the foreign substance has contacted the fabric fibers. Grass stains usually involve direct abrasive contact with vegetative matter thereby producing highly penetrating stains. Clay soil stains, although in some instances contacting the fabric fibers with less force, nevertheless provide a different type of soil removal problem du to the high degree of charge associated with the clay itself. This high surface charge density may act to repel some laundry adjunct ingredients, inter alia, clay dispersants, thereby resisting any appreciable solublizing of the clay into the laundry liquor.
A surfactant per se is not all that is necessary to remove unwanted clay soils and stains. In fact, not all surfactants work equally well on all types of stains. In addition to surfactants, polyamine hydrophilic soil dispersants are added to laundry detergent compositions to “carry away” clay soils from the fabric surface and to remove the possibility that the clay soil will be re-deposited upon the fabric. However, unless the clay can be initially solublized away from the fabric fiber, especially in the case of hydrophilic fibers, inter alia, cotton, there will be nothing in solution for the dispersants to chelate.
There is a long felt need in the art for laundry detergent compositions which can effectively solublize embedded clay and other hydrophilic soils from fabric. There has further been a long felt need for a method for cleaning hydrophilic soils from fabric wherein the hydrophilic soils are effectively solublized into the laundry liquor.